Phillies youngsters will dictate how much they have improved | Bob Brookover

Conventional wisdom when the duo of Phillies president Andy MacPhail and general manager Matt Klentak took control of the ballclub before the 2015 season suggested that a group of young players would grow into quality big-league players and then owner John Middleton, along with his partners – cousins Jim and Pete Buck — would provide the player payroll cash needed to push the team back into contention.

Predictably, not everything went according to plan, and yet, through their actions, Klentak and the Phillies obviously believe they are a contender again.

Players the Phillies thought would be part of their future are now part of their past. Instead of plugging in J.P. Crawford at shortstop, they used him as a trade chip to pry Jean Segura away from Seattle. Instead of becoming a powerful fixture at the catching position, Jorge Alfaro became a key ingredient in getting the Miami Marlins to part ways with J.T. Realmuto.

A long list of others – Cody Asche, Mark Appel, Brett Oberholtzer, Jake Thompson, and Tommy Joseph, to name a few – once considered prospects of the future have faded into oblivion. Only a handful have become definite fixtures in the Phillies’ future vision, which only proves how unpredictable the game is even for the people who are paid to scout or analyze players.

“When you’re at the early stages of a rebuild, one of the hardest things is to close your eyes and visualize what the roster is going to look like when you get back to the playoffs,” Klentak said last week. “It’s hard. You don’t know. You trust that your process is sound. You trust in your player-development group. You trust in your scouts. But you don’t have an exact road map for how that’s going to play out or when that’s going to play out.”

Nick Pivetta is one of the Phillies' young starting pitches who must come through this season.

Despite discarding younger players for older ones this offseason in an effort to return to the playoffs for the first time since 2011, the Phillies have actually remained one of the youngest teams in baseball. They will, in fact, have the youngest starting eight in the National League East, and that will remain true even if they sign either Bryce Harper or Manny Machado.

If they add Machado, the average starting age of 27.75 will remain intact because he would likely replace Maikel Franco as the team’s starting third baseman. Both players will be 26 for most of the 2019 season. Should they sign Harper, the average age of their starting lineup would tick up to 27.87. Harper will play this season at age 26. Nick Williams, the player he would likely replace, is 25.

It’s saying something that the Phillies will have the youngest lineup, because the Atlanta Braves have a 21-year-old star outfielder in Ronald Acuna Jr. and a 22-year-old second baseman in Ozzie Albies. They also have three players (Josh Donaldson, 33, Nick Markakis, 35, and Tyler Flowers, 33) over the age of 30. The Phillies’ only projected starter over 30 is 32-year-old outfielder Andrew McCutchen.

The Phillies’ starting eight is just slightly younger than the Washington Nationals', whose starting eight averages 28. The Nats have two young rising stars in Juan Soto (20) and Victor Robles (22 in May), but they also have four players (Adam Eaton, 30; Brian Dozier, 32 in May; Ryan Zimmerman, 34; and Yan Gomes, 31) over 30.

JOSE F. MORENO / Staff Photographer

Free-agent addition Andrew McCutchen, 32, will be the Phillies' only regular position player over the age of 30 this season.

The Mets feel good about what they did this offseason, but the average age of their starting lineup is 30 and that’s without 33-year-old Yoenis Cespedes, who could open the season on the disabled list. They have five players over 30.

Surprisingly, the rebuilding Marlins have a projected starting eight with an average age of nearly 30 years old, which is an indication that they are a long way from being good again.

Only the Braves, at 26.4, have a younger projected starting rotation than the Phillies, who check in at 27.4 with four of their five guys 27 years or younger.

It is a good thing that the Phillies are a young team and also ready to contend again, but the development of some of their under-30 players ultimately will decide whether they really are ready for contention. That is especially true in the pitching department. Can Aaron Nola repeat the best season of his career? Are Nick Pivetta, Vince Velasquez, and Zach Eflin ready to be quality major-league starters? The Phillies’ goal of 90-plus wins probably will not be achievable if the rotation is not as good as management thinks it can be.

Is Cesar Hernandez an elite second baseman as he showed for much of 2017 and the first half of 2018 or is he an inconsistent enigma? Will Franco ever live up to the top-prospect potential that was bestowed upon him a half decade ago? Will all that time the Phillies spent pushing Odubel Herrera this winter make a difference in 2019? Can Williams be good enough if Harper is not here?

The Phillies appear to be considerably better, but they also remain relatively young. That youth will determine how far forward the Phillies can go.